Several patents and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains. The entire disclosure of each of these patents and publications is incorporated by reference herein.
Premium golf balls include wound balls, two-piece balls and multilayered balls. Wound balls may have a spherical molded center, elastomeric thread-like material wound around the center, and either a thermoplastic or thermoset cover. Two-piece balls have a spherical molded core covered with a thin layer of thermoplastic or thermoset material. Multilayered balls have a spherical molded core, a cover, and one or more intermediate layers between the core and the cover.
Thermoplastic ionomers of copolymers of α-olefins, particularly ethylene, and C3-8 α,β-ethylenically unsaturated carboxylic acids have found utility in golf ball components such as covers, and other applications. See, e.g., U.S. Pat. No. 3,264,272.
Ionomers have also been modified with fatty acids. For example, U.S. Pat. No. 6,777,472 discloses a melt-processable thermoplastic composition consisting essentially of (a) from 20 to 45% aliphatic, mono-functional organic acid(s) having fewer than 36 carbon atoms or salt(s) thereof; and (b) ethylene, C3 to C8 α,β-ethylenically unsaturated carboxylic acid copolymer(s) or melt-processible ionomer(s) thereof, wherein greater than 90% of all the acid of (a) and (b) is neutralized by concurrently or subsequently adding to the melt blend of (a) and (b) an amount of a cation source necessary to obtain greater than 90% neutralization.
Modified ionomers have been used as golf ball components. For example, U.S. Pat. No. 6,565,456 discloses multilayer golf balls comprising a solid core, a surrounding layer, an intermediate layer and a cover, wherein at least one of the surrounding layer, the intermediate layer or the cover is formed of a heated mixture comprising (a) an olefin-carboxylic acid-optional carboxylate random copolymer and/or (d) a metal ion-neutralized olefin-carboxylic acid-optional carboxylate random copolymer; (b) a fatty acid or derivative; and (c) a neutralizing basic inorganic metal compound.
U.S. Pat. No. 6,653,382 discloses golf balls comprising a thermoplastic polymer consisting essentially of at least one of (a) E/X/Y copolymers where E is ethylene, X is a C3-8 α,β-ethylenically unsaturated carboxylic acid, and Y is a softening comonomer of the E/X/Y copolymers, wherein X is about 3-30% of the E/X/Y copolymer, or partially neutralized ionomers thereof, and Y is about 0-30% of the E/X/Y copolymer; and (b) one or more aliphatic, mono-functional organic acids having fewer than 36 carbon atoms or salts thereof being present in the range of about 25 to about 150 parts per hundred parts by weight of the E/X/Y copolymer, wherein greater than 90% of all the acid of (a) and of (b) is neutralized with a cation source.
US2002/0111407 discloses golf balls comprising a base resin comprising a (metal ion-neutralized) olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary random copolymer and optionally a (metal ion-neutralized) olefin-unsaturated carboxylic acid binary random copolymer blended with specific proportions of a fatty acid and/or fatty acid derivative and a basic inorganic metal compound capable of neutralizing acidic groups left unneutralized in the base resin and fatty acid.
U.S. Pat. No. 6,953,820 discloses a composition, and golf balls comprising the composition, comprising a thermoplastic polymer blend which has a coefficient of restitution of at least 0.785 and an Atti compression of no more than 100, wherein the blend consists essentially of at least one (a) E/X/Y copolymers where E is ethylene, X is a mixture of at least two C3 to C8 α,β-ethylenically unsaturated carboxylic acids, and Y is a softening comonomer or ionomers of the E/X/Y copolymers wherein X is about 3-30% of the E/X/Y copolymer, and Y is 0 to about 30% of the E/X/Y copolymer; and (b) one or more aliphatic, mono-functional organic acids having fewer than 36 carbon atoms or salts thereof, wherein greater than 90% of all the acid of (a) and of (b) is neutralized.
See also U.S. Pat. Nos. 6,815,489. 7,375,151, US2005/0267240, US2007/0203277, US2009/0118040, and EP1124898B1 (organic acid-modified ionomer compositions and their use in golf balls because of their high resilience, but their stiffness may be too low for certain golf ball constructions).
Thermoplastic compositions such as those described above have been modified with various inorganic fillers to reduce cost, to affect rheological, mixing and physical properties such as density, flex modulus, hardness (e.g. Shore D), mold release, melt flow index and the like, and/or reinforce the material. For example, the compositions have been modified by blending with a wide range of density-adjusting fillers, e.g., ceramics, glass spheres (solid or hollow, and filled or unfilled), and fibers, inorganic particles, and metal particles, such as metal flakes, metallic powders, oxides, and derivatives thereof. For example, see U.S. Pat. Nos. 7,156,755 and 7,361,101.
Fillers have also been used to modify the density of the compositions to adjust the weight of the golf ball to meet required limits, by imparting additional density to the compositions. The amount of filler employed is primarily a function of weight requirements and desired weight distribution of the golf ball. Filler may be included in one or more layers of the golf ball, such as the core or intermediate layer(s), the selection being dependent upon the type of golf ball desired (i.e., two-piece, wound or multilayer).
In golf balls it is increasingly desirable to use intermediate layers (“mantles” or “inner covers”, or “outer cores”) that have properties including high resilience, high stiffness, and moisture barrier to enable optimum velocity, spin, feel, and playability. It is also sometimes desirable to move weight from the core to the outer layer(s) of the golf ball.
Thus, it is desirable to prepare compositions suitable for use in a golf ball that provide a combination of such properties.